Structures of Eukaryotic Cells

There are certain features which all eukaryotic cells share. They are all relatively large cells (compared to prokaryotic cells), and they all have their DNA enclosed in a nucleus.

In terms of sub-cellular structures, all eukaryotic cells have a cell membrane, cytoplasm, nucleus, ribosomes and mitochondria.

Some types of eukaryotic cells also have other sub-cellular structures: plant cells and algal cells have chloroplasts, a vacuole and a cell wall.

The structures of animal, plant and algal cells are shown below. The functions of the various sub-cellular structures will be explained on a later page. For now, we will just focus on which cells have which sub-cellular structures.

Animal cells

Animal cells have the following sub-cellular structures:

  • Nucleus - which contains the cell's DNA.
  • Cell membrane - the membrane which surrounds the cell.
  • Cytoplasm - the fluid which fills the cell.
  • Ribosomes - which appear as small dots in the cytoplasm.
  • Mitochondria - round, red structures within the cytoplasm.
Labelled diagram of an animal cell. The cell is a big blob. The outer boundary of the cell is the cell membrane. It contains a large circular structure called the nucleus. The fluid within the cell is the cytoplasm. There are small dots within the cell called ribosomes. There are also small red structures called mitochondria.

Diagram of an animal cell, with its sub-cellular structures labelled.

Light microscope image of animal cells. Four cells are visible. In each cell there is a large blue nucleus, about a hundred small red mitochondria and large amounts of a protein called actin, which is green. These colours are not the actual colours of the structures, but are the colours of fluorescent dyes that have been added to the cells.

Microscope image of animal cells. These cells are from a cow's pulmonary artery. They have been stained with three fluorescent stains: one that turns the nucleus blue, one that turns the mitochondria red and one that turns a protein called actin green. Image: Erin Rod on Wikimedia Commons (CC BY 4.0)

Plant cells

Plant cells have all of the same sub-cellular structures as animal cells. In addition, they have:

  • Chloroplasts - round, green structures within the cytoplasm.
  • Vacuole - a large sac containing a fluid called cell sap.
  • Cell wall - A rigid wall around the outside of the cell membrane. It is made of a substance called cellulose.
Labelled diagram of a plant cell. Around the outside out the cell is a thick cell wall. The outer edges of the cell are straight lines. Within the cell wall is the cell membrane. The fluid within the cell membrane is the cytoplasm. Within the cytoplasm there is a nucleus, several mitochondria, chloroplasts and ribosomes and a vacuole (a large sac).

A plant cell, with its sub-cellular structures labelled.

Light microscope image of plant cells. About 100 to 200 cells are visible. The cell walls appear pale coloured, whereas the cells are packed full of bright green chloroplasts. The chloroplasts look like small sacks within the cells.

Light microscope image of cells from a plant called Hart's-tongue Thyme-moss. Cell walls and chloroplasts are visible.

Algal cells

Algal cells (the cells of algae) have all of the same sub-cellular structures as plant cells, including a cell wall made out of cellulose. This is because plants and algae are closely related.

Labelled diagram of an algal cell. Around the outside out the cell is a thick cell wall. The outer edge of the cell is a circle. Within the cell wall is the cell membrane. The fluid within the cell membrane is the cytoplasm. Within the cytoplasm there is a nucleus, several mitochondria, chloroplasts and ribosomes and a vacuole (a large sac).

An algal cell, with its sub-cellular structures labelled.

Electron microscope image of an algal cell. The image is black and white. The cell is roughly round. Several round structures are visible within the cell, including the nucleus. There are also what appear to be long filaments throughout the cytoplasm.

An algal cell viewed through an electron microscope

Flashcards

Flashcards help you memorise information quickly. Copy each question onto its own flashcard and then write the answer on the other side. Testing yourself on these regularly will enable you to learn much more quickly than just reading and making notes.

1/3

What features do all eukaryotic cells share?

2/3

Which sub-cellular structures are found in animal cells?

3/3

Which sub-cellular structures are found in plant and algal cells?

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